18 
BULLETIN 835t. U. 
DEPARTMENT OF AGRICULTURE. 
Except for the lighter .-oil- of the sandy type, the quantity of 
water required to move the moisture the first inch is about the same 
or a little less than to move it the last inch on a basis of 30-day 
tests. Table 3 brings out the fact that there is much less difference 
in the quantity of water required per inch for the various heights 
than is usually supposed. The difference in the percentage of mois- 
ture found near the bottom and the percentage found near the top 
of a vertical soil column containing capillary water raised from a 
free water surface leads to the natural conclusion that more water 
per inch is removed for the bottom inches than for the top inches. 
However, it i- observed that in flume 03 the reverse i- true, although 
the percentage of moisture near the bottom of this tiume was greater 
than it was within 4 inches of the top. Under another heading 
in this report is given at least a partial explanation of this apparent 
inconsistency. (See p. 56.) 
Table 
Watt ' Tom tank, by days, in percentage >>f total rem 
■ 
' 
I^mne. 
of days. 
43 
63 k ::■: 200 
1 
2 
10 
15 
20 
2 
61 
- 
91 
95 
Per cent. 
-:: 
66 
69 
72 
86 
91 
Percrr-. F 
34 
43 
55 60 
60 62 
;: 
-- 
93 : 87 
: : 
30 
-2 
53 
60 
■ 
92 
1 
■ : -. 
77 
82 
i 

: ; 
: ] 
100 
: 
Table.4 shows in general the relatively high percentage- of water 
removed from the tanks during the first day or two and the relatively 
small percentages used after the first three or four day-. It is f 
that in all flumes at the end of the third day. or one-tenth of the 30 
days, more than ,50 per cent of the water had been used, and by the 
end of the tenth day three-fourths of the total water used in 30 days 
had been removed from the tanks. During the last 10 days of the 
experiment only about 10 per cent of the total water was removed 
from the tank-, 
This table again indicates the longer continued use of the relatively 
large quantities of water by the heavier soils and the very rapid action 
of the lighter soils. This is of economic importance in that til.' 
for an extended time would be much less in proportion for a heavy 
soil than for a light soil where the lo.-- of water is caused by capillary 
action alone. 
